1. Field of the Invention
This invention pertains to a new and improved method for the preparation of selectively halogenated ketals and ketones from secondary alcohols or halohydrins, more specifically, selectively chlorinated or brominated ketals and ketones.
2. Description of the Prior Art
Heretofore, it has been extremely difficult to obtain selectively and symmetrically dihalogenated ketones and ketals. Oxidation of chlorohydrin (1-chloro-2-propanol) to chloroacetone has been reported in the literature to occur by any of the following reactions:
A. K.sub.2 Cr.sub.2 O.sub.7 + H.sub.2 SO.sub.4 PA1 b. HNO.sub.3 PA1 c. HOCl -- Markownikoff Ann. 153, 254-255 (1870) PA1 D. Ca(OCl).sub.2 -- Suknewitsch, Tschilingarjan Ber. 69, 1539 (1936).
None of the aforementioned references disclose or suggest oxidations by Cl.sub.2 or Br.sub.2. Farkas et al. in J. Am. Chem. Soc. 71, 2827 et seq., disclose the oxidation of alcohols by bromine in the presence of bromate ion. The object, however, of the Farkas et al. disclosure is to avoid substitution. Furthermore, there is no disclosure in Farkas et al. relative to selective and symmetrical dihalogenation. Additionally, prior art chlorinations and brominations yielded mixtures of halogenated ketones which were difficult to separate. The separation of isomers aspect of this invention is considered to be an additional novel feature of the instant application.